1. Field of the Invention:
The invention lies in the field of electronic communications. The invention relates to a method and device for maintaining environmental audio awareness in a simplex communications system.
2. Description of the Related Art:
Two general types of electronic audio two-way communications are used, simplex and duplex. In simplex communications, transmission and reception are communicated over a single communications channel. This means that when one user is transmitting over the channel, if another user transmits as well, neither can hear the other. A typical example of simplex communications is a two-way radio. In duplex communications, transmission and reception are each communicated over a separate communications channel; thus, transmission and reception do not interfere with one another. This means that two users can simultaneously talk to and receive from one another. A typical example of duplex communications is a cellular telephone.
Due to the portability of electronic transceiver units, the surrounding environment plays a significant role in overall quality of transmission and/or reception because the units can be taken, very quickly, from one kind of environment to another. Also, environmental conditions can change rapidly. With regard to reception, if the environment is noisy, then the user has difficulty hearing the, typically, low volume speaker output. To compensate for such an environment, therefore, the speaker can be adjusted by increasing volume or by equalizing the output signal towards frequencies easier to hear with high background noise in general or with the specific kind of background noise actually detected. As for transmission, a noisy environment plays an even greater role, in that, the background noise can, sometimes, completely overtake the communication message (i.e., user's voice), resulting in the receiving user primarily hearing the background noise or, even, only hearing the background noise.
Complex audio processing algorithms are employed to compensate for and/or reduce background noise. To perform such compensation and for correct performance, these algorithms require information relating to current characteristics of the environmental noise. Typically, this information is acquired by periodically sampling the environment. Specifically, the information is acquired by activating the input device in the transceiver unit (i.e., microphone) and measuring the audio environment. The detected audio environment at the input device, then, is used for regulating not only transmission, but also audio output from the receiving speaker of the same device.
Audio processing algorithms require a relatively continuous measurement of the audio environment at each end of a two-way communications link in order to provide environmental audio conditioning. In a duplex system, the microphone path is enabled continuously and can, therefore, provide a constant update of a possibly changing audio environment. In a typical two-way radio simplex system, however, only one path is running. Because the user enables the microphone path (and, therefore, the environmental detection functionality) manually in a simplex system, the environmental conditions of a simplex system are based on the last instance that the microphone path was on. Such manual activation is typically referred to as push-to-talk or PTT. It is, accordingly, possible for user to not enable their microphone path for a long period of time. Such a condition is risky for adequate audio environment compensation because the environmental conditions could have changed significantly since the last time the microphone path was enabled. In such a case, the audio-processing algorithm being employed loses track of the environmental conditions in which the unit is being exposed. Without relatively current information, the audio-processing algorithm will have a decrease in performance and, in some cases, will not be able to perform at all. A result of such behavior is a processing system that performs worse than the problem the algorithm was designed to prevent.
Another drawback to measurement of the audio environment is power usage. In a simplex communications system, power usage is critical because such a system typically uses batteries for the supply of power. If the audio environment were to be measured more often, then, as the monitoring uses up more battery power, less battery power is available for communications.